LXR linux/arch/powerpc/sysdev/mmio

   1/*
   2 * memory mapped NVRAM
   3 *
   4 * (C) Copyright IBM Corp. 2005
   5 *
   6 * Authors : Utz Bacher <utz.bacher@de.ibm.com>
   7 *
   8 * This program is free software; you can redistribute it and/or modify
   9 * it under the terms of the GNU General Public License as published by
  10 * the Free Software Foundation; either version 2, or (at your option)
  11 * any later version.
  12 *
  13 * This program is distributed in the hope that it will be useful,
  14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16 * GNU General Public License for more details.
  17 *
  18 * You should have received a copy of the GNU General Public License
  19 * along with this program; if not, write to the Free Software
  20 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  21 */
  22
  23#include <linux/fs.h>
  24#include <linux/init.h>
  25#include <linux/kernel.h>
  26#include <linux/spinlock.h>
  27#include <linux/types.h>
  28
  29#include <asm/machdep.h>
  30#include <asm/nvram.h>
  31#include <asm/prom.h>
  32
  33static void __iomem *mmio_nvram_start;
  34static long mmio_nvram_len;
  35static DEFINE_SPINLOCK(mmio_nvram_lock);
  36
  37static ssize_t mmio_nvram_read(char *buf, size_t count, loff_t *index)
  38{
  39        unsigned long flags;
  40
  41        if (*index >= mmio_nvram_len)
  42                return 0;
  43        if (*index + count > mmio_nvram_len)
  44                count = mmio_nvram_len - *index;
  45
  46        spin_lock_irqsave(&mmio_nvram_lock, flags);
  47
  48        memcpy_fromio(buf, mmio_nvram_start + *index, count);
  49
  50        spin_unlock_irqrestore(&mmio_nvram_lock, flags);
  51        
  52        *index += count;
  53        return count;
  54}
  55
  56static unsigned char mmio_nvram_read_val(int addr)
  57{
  58        unsigned long flags;
  59        unsigned char val;
  60
  61        if (addr >= mmio_nvram_len)
  62                return 0xff;
  63
  64        spin_lock_irqsave(&mmio_nvram_lock, flags);
  65
  66        val = ioread8(mmio_nvram_start + addr);
  67
  68        spin_unlock_irqrestore(&mmio_nvram_lock, flags);
  69
  70        return val;
  71}
  72
  73static ssize_t mmio_nvram_write(char *buf, size_t count, loff_t *index)
  74{
  75        unsigned long flags;
  76
  77        if (*index >= mmio_nvram_len)
  78                return 0;
  79        if (*index + count > mmio_nvram_len)
  80                count = mmio_nvram_len - *index;
  81
  82        spin_lock_irqsave(&mmio_nvram_lock, flags);
  83
  84        memcpy_toio(mmio_nvram_start + *index, buf, count);
  85
  86        spin_unlock_irqrestore(&mmio_nvram_lock, flags);
  87        
  88        *index += count;
  89        return count;
  90}
  91
  92static void mmio_nvram_write_val(int addr, unsigned char val)
  93{
  94        unsigned long flags;
  95
  96        if (addr < mmio_nvram_len) {
  97                spin_lock_irqsave(&mmio_nvram_lock, flags);
  98
  99                iowrite8(val, mmio_nvram_start + addr);
 100
 101                spin_unlock_irqrestore(&mmio_nvram_lock, flags);
 102        }
 103}
 104
 105static ssize_t mmio_nvram_get_size(void)
 106{
 107        return mmio_nvram_len;
 108}
 109
 110int __init mmio_nvram_init(void)
 111{
 112        struct device_node *nvram_node;
 113        unsigned long nvram_addr;
 114        struct resource r;
 115        int ret;
 116
 117        nvram_node = of_find_node_by_type(NULL, "nvram");
 118        if (!nvram_node)
 119                nvram_node = of_find_compatible_node(NULL, NULL, "nvram");
 120        if (!nvram_node) {
 121                printk(KERN_WARNING "nvram: no node found in device-tree\n");
 122                return -ENODEV;
 123        }
 124
 125        ret = of_address_to_resource(nvram_node, 0, &r);
 126        if (ret) {
 127                printk(KERN_WARNING "nvram: failed to get address (err %d)\n",
 128                       ret);
 129                goto out;
 130        }
 131        nvram_addr = r.start;
 132        mmio_nvram_len = resource_size(&r);
 133        if ( (!mmio_nvram_len) || (!nvram_addr) ) {
 134                printk(KERN_WARNING "nvram: address or length is 0\n");
 135                ret = -EIO;
 136                goto out;
 137        }
 138
 139        mmio_nvram_start = ioremap(nvram_addr, mmio_nvram_len);
 140        if (!mmio_nvram_start) {
 141                printk(KERN_WARNING "nvram: failed to ioremap\n");
 142                ret = -ENOMEM;
 143                goto out;
 144        }
 145
 146        printk(KERN_INFO "mmio NVRAM, %luk at 0x%lx mapped to %p\n",
 147               mmio_nvram_len >> 10, nvram_addr, mmio_nvram_start);
 148
 149        ppc_md.nvram_read_val   = mmio_nvram_read_val;
 150        ppc_md.nvram_write_val  = mmio_nvram_write_val;
 151        ppc_md.nvram_read       = mmio_nvram_read;
 152        ppc_md.nvram_write      = mmio_nvram_write;
 153        ppc_md.nvram_size       = mmio_nvram_get_size;
 154
 155out:
 156        of_node_put(nvram_node);
 157        return ret;
 158}
 159